The sutema: a
stabilizing chamber SideStoke
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As
is commonly the case with terms taken out of their original
cultural context, the word anagama is applied to a variety
of kiln designs. To me it suggests a single chambered climbing
kiln, longer than it is wide, and used for extended wood firings
with the aim of exploiting natural ash deposits. If stabilizing
chambers become the norm I may have to change my expectations to
include a second chamber, as advocated by the late Michio
Furutani. He introduced a smaller second chamber to his anagamas,
located between the main chamber and the chimney. He called the
second chamber a sutema(pronounce that something
like stemma). Its primary purpose is to stabilize the
firing conditions in the main chamber, although some pots may be
fired in the sutema if external access is available. The volume
of the sutema as advocated by Furutani ranged from relatively
small up to nearly half the volume of the main chamber. He
maintained that a sutema made a kiln easier to control and
improved the front to back heat distribution.

An
article by Bede Clarke in the Log
Book issue 27 reports
that a sutema will reduce the amount of smoke issuing from the
chimney during heavy stokings, and an injection of forced air
into the the sutema will eliminate the smoke completely.

Transverse
sutema

Integral
sutema

When
it comes to construction of a sutema there are two obvious options:
partition off the rear section of the anagama chamber, or construct a
separate chamber at the back of the main chamber, witan arch at right
angles to the main chamber arch.

The
advantage of the transverse sutema is that it is relatively easy to
build a door in one end to allow access to the chamber so that pots
can be fired in it. This is not necessarily a good practice as
worrying about conditions in the sutema may distract from
concentration on firing the main chamber. It is well known that
chasing too many rabbits at once may decrease your chances of
catching a meal.

An integral chamber
can be installed in an existing anagama, and if the wall built to
form the sutema is not too well tied into the existing arch there is
the possibility of changing the sutema size to fit the number of pots
ready to fire. This may well be useful for woodfirers who
overestimate their long term personal energy supply and make their
kilns too large. This is common amongst young players. Using high
precision measuring instruments scientists have shown conclusively
that woodfirers' brains get bigger as they get older, and their kilns
get smaller.